pacman::p_load(sf, raster, spatstat, tmap, tidyverse)Hands-on Exercise 3
1. Overview
Spatial Point Pattern Analysis examines the distribution pattern of points on a surface. These points can represent the locations of:
Events, such as crimes, traffic accidents, or disease outbreaks.
Business services, like coffee shops and fast food outlets, or facilities such as childcare and eldercare centers.
In this exercise, I utilize functions from the spatstat package to explore the spatial point processes of childcare centers in Singapore.
Key Questions:
Are the childcare centers in Singapore randomly distributed across the country?
If not, where are the areas with a higher concentration of childcare centers?
2. The Data
To answer these questions, I used three datasets:
CHILDCARE: A point dataset with location and attribute information for childcare centers in Singapore. This dataset, in GeoJSON format, was downloaded from Data.gov.sg.MP14_SUBZONE_WEB_PL: A polygon dataset representing the 2014 Master Plan Planning Subzone boundaries provided by the Urban Redevelopment Authority (URA) in ESRI Shapefile format, also from Data.gov.sg.CostalOutline: A polygon dataset outlining the national boundary of Singapore, provided by the Singapore Land Authority (SLA) in ESRI Shapefile format.
3. Installing and Loading the R Packages
I installed and loaded the necessary R packages to handle spatial data, perform point pattern analysis, and create thematic maps:
pacman::p_load(): Ensures that the required packages are installed and loaded. The packages include:sf: For handling and analyzing spatial vector data.raster: For raster data manipulation.spatstat: For spatial point pattern analysis.tmap: For creating thematic maps.tidyverse: For general data manipulation and visualization.
4. Spatial Data Wrangling
4.1 Importing the Spatial Data
I imported the datasets and ensured they all use the same coordinate reference system (CRS) for consistency in spatial analysis.
childcare_sf <- st_read("data/child-care-services-geojson.geojson") %>%
st_transform(crs = 3414)Reading layer `child-care-services-geojson' from data source
`C:\EasonXu-HY99\IS415\Hands-on_Ex\Hands-on_Ex03\data\child-care-services-geojson.geojson'
using driver `GeoJSON'
Simple feature collection with 1545 features and 2 fields
Geometry type: POINT
Dimension: XYZ
Bounding box: xmin: 103.6824 ymin: 1.248403 xmax: 103.9897 ymax: 1.462134
z_range: zmin: 0 zmax: 0
Geodetic CRS: WGS 84st_transform(): Converts the spatial data to the Singapore-specific projected CRS (EPSG: 3414).
sg_sf <- st_read(dsn = "data", layer = "CostalOutline") Reading layer `CostalOutline' from data source
`C:\EasonXu-HY99\IS415\Hands-on_Ex\Hands-on_Ex03\data' using driver `ESRI Shapefile'
Simple feature collection with 60 features and 4 fields
Geometry type: POLYGON
Dimension: XY
Bounding box: xmin: 2663.926 ymin: 16357.98 xmax: 56047.79 ymax: 50244.03
Projected CRS: SVY21mpsz_sf <- st_read(dsn = "data", layer = "MP14_SUBZONE_WEB_PL")Reading layer `MP14_SUBZONE_WEB_PL' from data source
`C:\EasonXu-HY99\IS415\Hands-on_Ex\Hands-on_Ex03\data' using driver `ESRI Shapefile'
Simple feature collection with 323 features and 15 fields
Geometry type: MULTIPOLYGON
Dimension: XY
Bounding box: xmin: 2667.538 ymin: 15748.72 xmax: 56396.44 ymax: 50256.33
Projected CRS: SVY21st_crs(childcare_sf) Coordinate Reference System:
User input: EPSG:3414
wkt:
PROJCRS["SVY21 / Singapore TM",
BASEGEOGCRS["SVY21",
DATUM["SVY21",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]]],
PRIMEM["Greenwich",0,
ANGLEUNIT["degree",0.0174532925199433]],
ID["EPSG",4757]],
CONVERSION["Singapore Transverse Mercator",
METHOD["Transverse Mercator",
ID["EPSG",9807]],
PARAMETER["Latitude of natural origin",1.36666666666667,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8801]],
PARAMETER["Longitude of natural origin",103.833333333333,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8802]],
PARAMETER["Scale factor at natural origin",1,
SCALEUNIT["unity",1],
ID["EPSG",8805]],
PARAMETER["False easting",28001.642,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",38744.572,
LENGTHUNIT["metre",1],
ID["EPSG",8807]]],
CS[Cartesian,2],
AXIS["northing (N)",north,
ORDER[1],
LENGTHUNIT["metre",1]],
AXIS["easting (E)",east,
ORDER[2],
LENGTHUNIT["metre",1]],
USAGE[
SCOPE["Cadastre, engineering survey, topographic mapping."],
AREA["Singapore - onshore and offshore."],
BBOX[1.13,103.59,1.47,104.07]],
ID["EPSG",3414]]st_crs(mpsz_sf) Coordinate Reference System:
User input: SVY21
wkt:
PROJCRS["SVY21",
BASEGEOGCRS["SVY21[WGS84]",
DATUM["World Geodetic System 1984",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]],
ID["EPSG",6326]],
PRIMEM["Greenwich",0,
ANGLEUNIT["Degree",0.0174532925199433]]],
CONVERSION["unnamed",
METHOD["Transverse Mercator",
ID["EPSG",9807]],
PARAMETER["Latitude of natural origin",1.36666666666667,
ANGLEUNIT["Degree",0.0174532925199433],
ID["EPSG",8801]],
PARAMETER["Longitude of natural origin",103.833333333333,
ANGLEUNIT["Degree",0.0174532925199433],
ID["EPSG",8802]],
PARAMETER["Scale factor at natural origin",1,
SCALEUNIT["unity",1],
ID["EPSG",8805]],
PARAMETER["False easting",28001.642,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",38744.572,
LENGTHUNIT["metre",1],
ID["EPSG",8807]]],
CS[Cartesian,2],
AXIS["(E)",east,
ORDER[1],
LENGTHUNIT["metre",1,
ID["EPSG",9001]]],
AXIS["(N)",north,
ORDER[2],
LENGTHUNIT["metre",1,
ID["EPSG",9001]]]]st_crs(sg_sf)Coordinate Reference System:
User input: SVY21
wkt:
PROJCRS["SVY21",
BASEGEOGCRS["SVY21[WGS84]",
DATUM["World Geodetic System 1984",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]],
ID["EPSG",6326]],
PRIMEM["Greenwich",0,
ANGLEUNIT["Degree",0.0174532925199433]]],
CONVERSION["unnamed",
METHOD["Transverse Mercator",
ID["EPSG",9807]],
PARAMETER["Latitude of natural origin",1.36666666666667,
ANGLEUNIT["Degree",0.0174532925199433],
ID["EPSG",8801]],
PARAMETER["Longitude of natural origin",103.833333333333,
ANGLEUNIT["Degree",0.0174532925199433],
ID["EPSG",8802]],
PARAMETER["Scale factor at natural origin",1,
SCALEUNIT["unity",1],
ID["EPSG",8805]],
PARAMETER["False easting",28001.642,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",38744.572,
LENGTHUNIT["metre",1],
ID["EPSG",8807]]],
CS[Cartesian,2],
AXIS["(E)",east,
ORDER[1],
LENGTHUNIT["metre",1,
ID["EPSG",9001]]],
AXIS["(N)",north,
ORDER[2],
LENGTHUNIT["metre",1,
ID["EPSG",9001]]]]st_crs(): Checks the CRS of each dataset to ensure they are compatible for spatial operations.
mpsz_sf <- st_set_crs(mpsz_sf, 3414)Warning: st_crs<- : replacing crs does not reproject data; use st_transform for
thatsg_sf <- st_set_crs(sg_sf, 3414)Warning: st_crs<- : replacing crs does not reproject data; use st_transform for
thatst_set_crs(): Assigns the specified CRS (EPSG: 3414) to the datasets if not already defined, ensuring all datasets are in the same spatial reference.
childcare_sf <- st_transform(childcare_sf, crs = 3414)- Re-applied the transformation to make sure the childcare dataset uses the correct CRS.
st_crs(childcare_sf)Coordinate Reference System:
User input: EPSG:3414
wkt:
PROJCRS["SVY21 / Singapore TM",
BASEGEOGCRS["SVY21",
DATUM["SVY21",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]]],
PRIMEM["Greenwich",0,
ANGLEUNIT["degree",0.0174532925199433]],
ID["EPSG",4757]],
CONVERSION["Singapore Transverse Mercator",
METHOD["Transverse Mercator",
ID["EPSG",9807]],
PARAMETER["Latitude of natural origin",1.36666666666667,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8801]],
PARAMETER["Longitude of natural origin",103.833333333333,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8802]],
PARAMETER["Scale factor at natural origin",1,
SCALEUNIT["unity",1],
ID["EPSG",8805]],
PARAMETER["False easting",28001.642,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",38744.572,
LENGTHUNIT["metre",1],
ID["EPSG",8807]]],
CS[Cartesian,2],
AXIS["northing (N)",north,
ORDER[1],
LENGTHUNIT["metre",1]],
AXIS["easting (E)",east,
ORDER[2],
LENGTHUNIT["metre",1]],
USAGE[
SCOPE["Cadastre, engineering survey, topographic mapping."],
AREA["Singapore - onshore and offshore."],
BBOX[1.13,103.59,1.47,104.07]],
ID["EPSG",3414]]st_crs(mpsz_sf)Coordinate Reference System:
User input: EPSG:3414
wkt:
PROJCRS["SVY21 / Singapore TM",
BASEGEOGCRS["SVY21",
DATUM["SVY21",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]]],
PRIMEM["Greenwich",0,
ANGLEUNIT["degree",0.0174532925199433]],
ID["EPSG",4757]],
CONVERSION["Singapore Transverse Mercator",
METHOD["Transverse Mercator",
ID["EPSG",9807]],
PARAMETER["Latitude of natural origin",1.36666666666667,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8801]],
PARAMETER["Longitude of natural origin",103.833333333333,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8802]],
PARAMETER["Scale factor at natural origin",1,
SCALEUNIT["unity",1],
ID["EPSG",8805]],
PARAMETER["False easting",28001.642,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",38744.572,
LENGTHUNIT["metre",1],
ID["EPSG",8807]]],
CS[Cartesian,2],
AXIS["northing (N)",north,
ORDER[1],
LENGTHUNIT["metre",1]],
AXIS["easting (E)",east,
ORDER[2],
LENGTHUNIT["metre",1]],
USAGE[
SCOPE["Cadastre, engineering survey, topographic mapping."],
AREA["Singapore - onshore and offshore."],
BBOX[1.13,103.59,1.47,104.07]],
ID["EPSG",3414]]st_crs(sg_sf)Coordinate Reference System:
User input: EPSG:3414
wkt:
PROJCRS["SVY21 / Singapore TM",
BASEGEOGCRS["SVY21",
DATUM["SVY21",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]]],
PRIMEM["Greenwich",0,
ANGLEUNIT["degree",0.0174532925199433]],
ID["EPSG",4757]],
CONVERSION["Singapore Transverse Mercator",
METHOD["Transverse Mercator",
ID["EPSG",9807]],
PARAMETER["Latitude of natural origin",1.36666666666667,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8801]],
PARAMETER["Longitude of natural origin",103.833333333333,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8802]],
PARAMETER["Scale factor at natural origin",1,
SCALEUNIT["unity",1],
ID["EPSG",8805]],
PARAMETER["False easting",28001.642,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",38744.572,
LENGTHUNIT["metre",1],
ID["EPSG",8807]]],
CS[Cartesian,2],
AXIS["northing (N)",north,
ORDER[1],
LENGTHUNIT["metre",1]],
AXIS["easting (E)",east,
ORDER[2],
LENGTHUNIT["metre",1]],
USAGE[
SCOPE["Cadastre, engineering survey, topographic mapping."],
AREA["Singapore - onshore and offshore."],
BBOX[1.13,103.59,1.47,104.07]],
ID["EPSG",3414]]- Confirmed the CRS settings for all datasets.
4.2 Mapping the Geospatial Data Sets
To visualize the spatial datasets, I created static and interactive maps using the tmap package:
tmap_mode("plot")tmap mode set to plottingtm_shape(sg_sf) +
tm_polygons(col = "grey", border.col = "black") +
tm_shape(mpsz_sf) +
tm_polygons(col = "grey", border.col = "black") +
tm_shape(childcare_sf) +
tm_dots(col = "black", size = 0.1)
tmap_mode("plot"): Sets the mode for static plotting.tm_shape(): Specifies the spatial object to be used in the map.tm_polygons(): Plots polygon features with specified fill and border colors.tm_dots(): Adds point symbols to the map for representing the childcare centers.
For an interactive map:
tmap_mode('view')tmap mode set to interactive viewingtm_shape(childcare_sf) + tm_dots()tmap_mode('view'): Switches to interactive viewing mode, allowing dynamic exploration of the spatial data.
Returning to static plotting mode:
tmap_mode('plot')tmap mode set to plotting- Resets to static plotting after using the interactive mode.
5. Geospatial Data Wrangling
5.1 Converting sf Data Frames to sp’s Spatial* Class
To perform certain spatial analyses, I needed to convert sf data frames into sp’s Spatial* class objects.
childcare <- as_Spatial(childcare_sf)
mpsz <- as_Spatial(mpsz_sf)
sg <- as_Spatial(sg_sf)as_Spatial(): Converts ansfobject into anspobject.
summary(childcare)Object of class SpatialPointsDataFrame
Coordinates:
min max
coords.x1 11203.01 45404.24
coords.x2 25667.60 49300.88
coords.x3 0.00 0.00
Is projected: TRUE
proj4string :
[+proj=tmerc +lat_0=1.36666666666667 +lon_0=103.833333333333 +k=1
+x_0=28001.642 +y_0=38744.572 +ellps=WGS84 +towgs84=0,0,0,0,0,0,0
+units=m +no_defs]
Number of points: 1545
Data attributes:
Name Description
Length:1545 Length:1545
Class :character Class :character
Mode :character Mode :character summary(mpsz)Object of class SpatialPolygonsDataFrame
Coordinates:
min max
x 2667.538 56396.44
y 15748.721 50256.33
Is projected: TRUE
proj4string :
[+proj=tmerc +lat_0=1.36666666666667 +lon_0=103.833333333333 +k=1
+x_0=28001.642 +y_0=38744.572 +ellps=WGS84 +towgs84=0,0,0,0,0,0,0
+units=m +no_defs]
Data attributes:
OBJECTID SUBZONE_NO SUBZONE_N SUBZONE_C
Min. : 1.0 Min. : 1.000 Length:323 Length:323
1st Qu.: 81.5 1st Qu.: 2.000 Class :character Class :character
Median :162.0 Median : 4.000 Mode :character Mode :character
Mean :162.0 Mean : 4.625
3rd Qu.:242.5 3rd Qu.: 6.500
Max. :323.0 Max. :17.000
CA_IND PLN_AREA_N PLN_AREA_C REGION_N
Length:323 Length:323 Length:323 Length:323
Class :character Class :character Class :character Class :character
Mode :character Mode :character Mode :character Mode :character
REGION_C INC_CRC FMEL_UPD_D X_ADDR
Length:323 Length:323 Min. :2014-12-05 Min. : 5093
Class :character Class :character 1st Qu.:2014-12-05 1st Qu.:21864
Mode :character Mode :character Median :2014-12-05 Median :28465
Mean :2014-12-05 Mean :27257
3rd Qu.:2014-12-05 3rd Qu.:31674
Max. :2014-12-05 Max. :50425
Y_ADDR SHAPE_Leng SHAPE_Area
Min. :19579 Min. : 871.5 Min. : 39438
1st Qu.:31776 1st Qu.: 3709.6 1st Qu.: 628261
Median :35113 Median : 5211.9 Median : 1229894
Mean :36106 Mean : 6524.4 Mean : 2420882
3rd Qu.:39869 3rd Qu.: 6942.6 3rd Qu.: 2106483
Max. :49553 Max. :68083.9 Max. :69748299 summary(sg)Object of class SpatialPolygonsDataFrame
Coordinates:
min max
x 2663.926 56047.79
y 16357.981 50244.03
Is projected: TRUE
proj4string :
[+proj=tmerc +lat_0=1.36666666666667 +lon_0=103.833333333333 +k=1
+x_0=28001.642 +y_0=38744.572 +ellps=WGS84 +towgs84=0,0,0,0,0,0,0
+units=m +no_defs]
Data attributes:
GDO_GID MSLINK MAPID COSTAL_NAM
Min. : 1.00 Min. : 1.00 Min. :0 Length:60
1st Qu.:15.75 1st Qu.:17.75 1st Qu.:0 Class :character
Median :30.50 Median :33.50 Median :0 Mode :character
Mean :30.50 Mean :33.77 Mean :0
3rd Qu.:45.25 3rd Qu.:49.25 3rd Qu.:0
Max. :60.00 Max. :67.00 Max. :0 5.2 Converting the Spatial* Class into Generic sp Format
I further converted the sp objects into more generic formats used by other spatial analysis functions.
childcare_sp <- as(childcare, "SpatialPoints")
sg_sp <- as(sg, "SpatialPolygons")Why: Converting to generic
spformats allows compatibility with a wider range of functions and analyses in R.Functions:
as(): Converts objects from one class to another, in this case, converting to “SpatialPoints” and “SpatialPolygons”.
Checking the converted objects:
childcare_spclass : SpatialPoints
features : 1545
extent : 11203.01, 45404.24, 25667.6, 49300.88 (xmin, xmax, ymin, ymax)
crs : +proj=tmerc +lat_0=1.36666666666667 +lon_0=103.833333333333 +k=1 +x_0=28001.642 +y_0=38744.572 +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs sg_spclass : SpatialPolygons
features : 60
extent : 2663.926, 56047.79, 16357.98, 50244.03 (xmin, xmax, ymin, ymax)
crs : +proj=tmerc +lat_0=1.36666666666667 +lon_0=103.833333333333 +k=1 +x_0=28001.642 +y_0=38744.572 +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs - Challenge: Understanding the differences between the Spatial* classes and generic
spobjects is crucial for using the correct format in different analyses.
5.3 Converting the Generic sp Format into spatstat’s ppp Format
To analyze spatial point patterns using spatstat, I converted the generic sp objects into ppp (planar point pattern) format.
childcare_ppp <- as.ppp(childcare_sf)Warning in as.ppp.sf(childcare_sf): only first attribute column is used for
markschildcare_pppMarked planar point pattern: 1545 points
marks are of storage type 'character'
window: rectangle = [11203.01, 45404.24] x [25667.6, 49300.88] unitsWhy: The
pppformat is specifically designed for spatial point pattern analysis in spatstat.Functions:
as.ppp(): Converts spatial objects into thepppformat.
Visualizing and summarizing the ppp object:
plot(childcare_ppp)Warning in default.charmap(ntypes, chars): Too many types to display every type
as a different characterWarning: Only 10 out of 1545 symbols are shown in the symbol map
summary(childcare_ppp)Marked planar point pattern: 1545 points
Average intensity 1.91145e-06 points per square unit
Coordinates are given to 11 decimal places
marks are of type 'character'
Summary:
Length Class Mode
1545 character character
Window: rectangle = [11203.01, 45404.24] x [25667.6, 49300.88] units
(34200 x 23630 units)
Window area = 808287000 square unitsplot(): Visualizes the spatial distribution of points in thepppobject.summary(): Provides a detailed summary of thepppobject, including the number of points and window properties.
5.4 Handling Duplicated Points
I checked for and handled any duplicated points in the dataset to ensure the accuracy of the spatial analysis.
any(duplicated(childcare_ppp))[1] FALSEWhy: Detecting duplicated points is crucial as they can skew spatial point pattern analyses.
Functions:
any(): Checks if there are anyTRUEvalues in a logical vector, indicating duplicates in this case.duplicated(): Identifies duplicated points in thepppobject.
Checking the multiplicity of points:
multiplicity(childcare_ppp) [1] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[38] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[75] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[112] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[149] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[186] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[223] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[260] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[297] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[334] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[371] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[408] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[445] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[482] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[519] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[556] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[593] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[630] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[667] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[704] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[741] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[778] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[815] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[852] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[889] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[926] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[963] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1000] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1037] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1074] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1111] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1148] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1185] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1222] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1259] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1296] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1333] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1370] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1407] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1444] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1481] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
[1518] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1sum(multiplicity(childcare_ppp) > 1)[1] 0multiplicity(): Returns the number of times each point occurs.sum(): Sums the total number of duplicate points.
Visualizing duplicated points:
tmap_mode('view')tmap mode set to interactive viewingtm_shape(childcare) + tm_dots(alpha=0.4, size=0.05)tmap_mode('plot')tmap mode set to plotting- Why: Visualizing the data helps identify and understand the location and extent of duplicated points.
Handling duplicates by jittering points:
childcare_ppp_jit <- rjitter(childcare_ppp, retry=TRUE, nsim=1, drop=TRUE)any(duplicated(childcare_ppp_jit))[1] FALSErjitter(): Randomly displaces points to reduce overlap, helping to handle duplicates while retaining the general spatial pattern.
5.5 Creating owin Object
I created an owin object to define the observation window for point pattern analysis.
sg_owin <- as.owin(sg_sf)Why: Defining an observation window is necessary for controlling the area within which spatial point patterns are analyzed.
Functions:
as.owin(): Converts a spatial object into anowinobject, defining a spatial observation window.
Plotting and summarizing the owin object:
plot(sg_owin)
summary(sg_owin)Window: polygonal boundary
50 separate polygons (1 hole)
vertices area relative.area
polygon 1 (hole) 30 -7081.18 -9.76e-06
polygon 2 55 82537.90 1.14e-04
polygon 3 90 415092.00 5.72e-04
polygon 4 49 16698.60 2.30e-05
polygon 5 38 24249.20 3.34e-05
polygon 6 976 23344700.00 3.22e-02
polygon 7 721 1927950.00 2.66e-03
polygon 8 1992 9992170.00 1.38e-02
polygon 9 330 1118960.00 1.54e-03
polygon 10 175 925904.00 1.28e-03
polygon 11 115 928394.00 1.28e-03
polygon 12 24 6352.39 8.76e-06
polygon 13 190 202489.00 2.79e-04
polygon 14 37 10170.50 1.40e-05
polygon 15 25 16622.70 2.29e-05
polygon 16 10 2145.07 2.96e-06
polygon 17 66 16184.10 2.23e-05
polygon 18 5195 636837000.00 8.78e-01
polygon 19 76 312332.00 4.31e-04
polygon 20 627 31891300.00 4.40e-02
polygon 21 20 32842.00 4.53e-05
polygon 22 42 55831.70 7.70e-05
polygon 23 67 1313540.00 1.81e-03
polygon 24 734 4690930.00 6.47e-03
polygon 25 16 3194.60 4.40e-06
polygon 26 15 4872.96 6.72e-06
polygon 27 15 4464.20 6.15e-06
polygon 28 14 5466.74 7.54e-06
polygon 29 37 5261.94 7.25e-06
polygon 30 111 662927.00 9.14e-04
polygon 31 69 56313.40 7.76e-05
polygon 32 143 145139.00 2.00e-04
polygon 33 397 2488210.00 3.43e-03
polygon 34 90 115991.00 1.60e-04
polygon 35 98 62682.90 8.64e-05
polygon 36 165 338736.00 4.67e-04
polygon 37 130 94046.50 1.30e-04
polygon 38 93 430642.00 5.94e-04
polygon 39 16 2010.46 2.77e-06
polygon 40 415 3253840.00 4.49e-03
polygon 41 30 10838.20 1.49e-05
polygon 42 53 34400.30 4.74e-05
polygon 43 26 8347.58 1.15e-05
polygon 44 74 58223.40 8.03e-05
polygon 45 327 2169210.00 2.99e-03
polygon 46 177 467446.00 6.44e-04
polygon 47 46 699702.00 9.65e-04
polygon 48 6 16841.00 2.32e-05
polygon 49 13 70087.30 9.66e-05
polygon 50 4 9459.63 1.30e-05
enclosing rectangle: [2663.93, 56047.79] x [16357.98, 50244.03] units
(53380 x 33890 units)
Window area = 725376000 square units
Fraction of frame area: 0.4015.6 Combining Point Events Object and owin Object
I combined the ppp and owin objects to focus on the analysis within the specified spatial boundary.
childcareSG_ppp = childcare_ppp[sg_owin]summary(childcareSG_ppp)Marked planar point pattern: 1545 points
Average intensity 2.129929e-06 points per square unit
Coordinates are given to 11 decimal places
marks are of type 'character'
Summary:
Length Class Mode
1545 character character
Window: polygonal boundary
50 separate polygons (1 hole)
vertices area relative.area
polygon 1 (hole) 30 -7081.18 -9.76e-06
polygon 2 55 82537.90 1.14e-04
polygon 3 90 415092.00 5.72e-04
polygon 4 49 16698.60 2.30e-05
polygon 5 38 24249.20 3.34e-05
polygon 6 976 23344700.00 3.22e-02
polygon 7 721 1927950.00 2.66e-03
polygon 8 1992 9992170.00 1.38e-02
polygon 9 330 1118960.00 1.54e-03
polygon 10 175 925904.00 1.28e-03
polygon 11 115 928394.00 1.28e-03
polygon 12 24 6352.39 8.76e-06
polygon 13 190 202489.00 2.79e-04
polygon 14 37 10170.50 1.40e-05
polygon 15 25 16622.70 2.29e-05
polygon 16 10 2145.07 2.96e-06
polygon 17 66 16184.10 2.23e-05
polygon 18 5195 636837000.00 8.78e-01
polygon 19 76 312332.00 4.31e-04
polygon 20 627 31891300.00 4.40e-02
polygon 21 20 32842.00 4.53e-05
polygon 22 42 55831.70 7.70e-05
polygon 23 67 1313540.00 1.81e-03
polygon 24 734 4690930.00 6.47e-03
polygon 25 16 3194.60 4.40e-06
polygon 26 15 4872.96 6.72e-06
polygon 27 15 4464.20 6.15e-06
polygon 28 14 5466.74 7.54e-06
polygon 29 37 5261.94 7.25e-06
polygon 30 111 662927.00 9.14e-04
polygon 31 69 56313.40 7.76e-05
polygon 32 143 145139.00 2.00e-04
polygon 33 397 2488210.00 3.43e-03
polygon 34 90 115991.00 1.60e-04
polygon 35 98 62682.90 8.64e-05
polygon 36 165 338736.00 4.67e-04
polygon 37 130 94046.50 1.30e-04
polygon 38 93 430642.00 5.94e-04
polygon 39 16 2010.46 2.77e-06
polygon 40 415 3253840.00 4.49e-03
polygon 41 30 10838.20 1.49e-05
polygon 42 53 34400.30 4.74e-05
polygon 43 26 8347.58 1.15e-05
polygon 44 74 58223.40 8.03e-05
polygon 45 327 2169210.00 2.99e-03
polygon 46 177 467446.00 6.44e-04
polygon 47 46 699702.00 9.65e-04
polygon 48 6 16841.00 2.32e-05
polygon 49 13 70087.30 9.66e-05
polygon 50 4 9459.63 1.30e-05
enclosing rectangle: [2663.93, 56047.79] x [16357.98, 50244.03] units
(53380 x 33890 units)
Window area = 725376000 square units
Fraction of frame area: 0.401plot(childcareSG_ppp)Warning in default.charmap(ntypes, chars): Too many types to display every type
as a different characterWarning: Only 10 out of 1545 symbols are shown in the symbol map
- Why: Combining the point events with the observation window ensures that the analysis is conducted only within the desired spatial extent.
6. First-Order Spatial Point Patterns Analysis
6.1 Kernel Density Estimation
6.1.1 Computing Kernel Density Estimation Using Automatic Bandwidth Selection Method
kde_childcareSG_bw <- density(childcareSG_ppp, sigma=bw.diggle, edge=TRUE, kernel="gaussian") plot(kde_childcareSG_bw)
bw <- bw.diggle(childcareSG_ppp)
bw sigma
298.4095 Why: Kernel Density Estimation (KDE) helps identify areas with higher point concentration. The bandwidth selection method (
bw.diggle) is used to optimize the KDE for the data’s distribution.Functions:
density(): Computes the KDE for the point pattern.bw.diggle(): Selects the bandwidth automatically using Diggle’s method, which is suitable for spatial data with edge corrections.
6.1.2 Rescaling KDE Values
childcareSG_ppp.km <- rescale.ppp(childcareSG_ppp, 1000, "km")kde_childcareSG.bw <- density(childcareSG_ppp.km, sigma=bw.diggle, edge=TRUE, kernel="gaussian")
plot(kde_childcareSG.bw)
Why: Rescaling helps in interpreting the KDE in a more familiar unit (e.g., kilometers).
Functions:
rescale.ppp(): Rescales the spatial coordinates of thepppobject.
6.2 Working with Different Automatic Bandwidth Methods
bw.CvL(childcareSG_ppp.km) sigma
4.543278 bw.scott(childcareSG_ppp.km) sigma.x sigma.y
2.224898 1.450966 bw.ppl(childcareSG_ppp.km) sigma
0.3897114 bw.diggle(childcareSG_ppp.km) sigma
0.2984095 Why: Exploring different bandwidth methods allows for comparison and selection of the best fit for the data.
Functions:
bw.CvL(),bw.scott(),bw.ppl(),bw.diggle(): Different methods for selecting the bandwidth in KDE.
Visualizing KDE with different bandwidths:
kde_childcareSG.ppl <- density(childcareSG_ppp.km, sigma=bw.ppl, edge=TRUE, kernel="gaussian")
par(mfrow=c(1,2))
plot(kde_childcareSG.bw, main = "bw.diggle")
plot(kde_childcareSG.ppl, main = "bw.ppl")
6.3 Working with Different Kernel Methods
par(mfrow=c(2,2))
plot(density(childcareSG_ppp.km, sigma=bw.ppl, edge=TRUE, kernel="gaussian"), main="Gaussian")
plot(density(childcareSG_ppp.km, sigma=bw.ppl, edge=TRUE, kernel="epanechnikov"), main="Epanechnikov")Warning in density.ppp(childcareSG_ppp.km, sigma = bw.ppl, edge = TRUE, :
Bandwidth selection will be based on Gaussian kernelplot(density(childcareSG_ppp.km, sigma=bw.ppl, edge=TRUE, kernel="quartic"), main="Quartic")Warning in density.ppp(childcareSG_ppp.km, sigma = bw.ppl, edge = TRUE, :
Bandwidth selection will be based on Gaussian kernelplot(density(childcareSG_ppp.km, sigma=bw.ppl, edge=TRUE, kernel="disc"), main="Disc")Warning in density.ppp(childcareSG_ppp.km, sigma = bw.ppl, edge = TRUE, :
Bandwidth selection will be based on Gaussian kernel
Why: Different kernel functions can affect the KDE results. Comparing different kernels helps determine the most appropriate method for the data.
Functions:
density()with differentkerneloptions (gaussian,epanechnikov,quartic,disc): Computes KDE using different smoothing kernels.
7. Fixed and Adaptive KDE
7.1 Computing KDE Using Fixed Bandwidth
kde_childcareSG_600 <- density(childcareSG_ppp.km, sigma=0.6, edge=TRUE, kernel="gaussian")
plot(kde_childcareSG_600)
Why: A fixed bandwidth KDE uses a constant smoothing parameter (sigma) across the entire study area, providing a uniform level of smoothing. This approach is useful for identifying general patterns in the distribution of points.
Functions:
density(): Computes kernel density estimates for point patterns. Thesigmaparameter specifies the bandwidth.
7.2 Computing KDE Using Adaptive Bandwidth
kde_childcareSG_adaptive <- adaptive.density(childcareSG_ppp.km, method="kernel")
plot(kde_childcareSG_adaptive)
Why: An adaptive bandwidth KDE adjusts the smoothing parameter based on local point density, providing finer detail in areas with high point concentration and smoother estimates in sparse areas. This method is useful for identifying local clusters.
Functions:
adaptive.density(): Computes KDE with adaptive bandwidth, adjusting the bandwidth according to point density.
Comparing fixed and adaptive bandwidth:
par(mfrow=c(1,2))
plot(kde_childcareSG.bw, main = "Fixed bandwidth")
plot(kde_childcareSG_adaptive, main = "Adaptive bandwidth")
- Why: Comparing both methods visually helps to understand how different bandwidth strategies affect the KDE.
7.3 Converting KDE Output into Grid Object
gridded_kde_childcareSG_bw <- as(kde_childcareSG.bw, "SpatialGridDataFrame")
spplot(gridded_kde_childcareSG_bw)
Why: Converting KDE output into a grid format allows for easier visualization and manipulation within various GIS tools.
Functions:
as(): Converts objects from one class to another.spplot(): Creates spatial plots of gridded data.
7.3.1 Converting Gridded Output into Raster
kde_childcareSG_bw_raster <- raster(kde_childcareSG.bw)kde_childcareSG_bw_rasterclass : RasterLayer
dimensions : 128, 128, 16384 (nrow, ncol, ncell)
resolution : 0.4170614, 0.2647348 (x, y)
extent : 2.663926, 56.04779, 16.35798, 50.24403 (xmin, xmax, ymin, ymax)
crs : NA
source : memory
names : layer
values : -8.476185e-15, 28.51831 (min, max)Why: Raster conversion facilitates the integration of KDE results with other raster-based analyses or visualization techniques.
Functions:
raster(): Converts a spatial object into a raster format.
7.3.2 Assigning Projection Systems
projection(kde_childcareSG_bw_raster) <- CRS("+init=EPSG:3414")
kde_childcareSG_bw_rasterclass : RasterLayer
dimensions : 128, 128, 16384 (nrow, ncol, ncell)
resolution : 0.4170614, 0.2647348 (x, y)
extent : 2.663926, 56.04779, 16.35798, 50.24403 (xmin, xmax, ymin, ymax)
crs : +proj=tmerc +lat_0=1.36666666666667 +lon_0=103.833333333333 +k=1 +x_0=28001.642 +y_0=38744.572 +ellps=WGS84 +units=m +no_defs
source : memory
names : layer
values : -8.476185e-15, 28.51831 (min, max)Why: Assigning the correct CRS ensures that spatial analyses and visualizations are accurate and geographically meaningful.
Functions:
projection(): Assigns or retrieves the CRS of a raster object.
7.4 Visualizing the Output in tmap
tm_shape(kde_childcareSG_bw_raster) +
tm_raster("layer", palette = "viridis") +
tm_layout(legend.position = c("right", "bottom"), frame = FALSE)
Why: Visualizing KDE results with
tmapprovides a more intuitive and aesthetically pleasing representation of spatial data.Functions:
tm_shape(): Specifies the spatial object to be visualized.tm_raster(): Visualizes raster data with a color gradient.tm_layout(): Customizes the layout of the map.
7.5 Comparing Spatial Point Patterns Using KDE
7.5.1 Extracting Study Areas
pg <- mpsz_sf %>%
filter(PLN_AREA_N == "PUNGGOL")
tm <- mpsz_sf %>%
filter(PLN_AREA_N == "TAMPINES")
ck <- mpsz_sf %>%
filter(PLN_AREA_N == "CHOA CHU KANG")
jw <- mpsz_sf %>%
filter(PLN_AREA_N == "JURONG WEST")Why: Extracting specific study areas allows focused analysis on different regions to compare spatial point patterns.
Functions:
filter(): Subsets data based on specified conditions.
Plotting study areas:
par(mfrow=c(2,2))
plot(pg, main = "Ponggol")Warning: plotting the first 9 out of 15 attributes; use max.plot = 15 to plot
all
plot(tm, main = "Tampines")Warning: plotting the first 9 out of 15 attributes; use max.plot = 15 to plot
all
plot(ck, main = "Choa Chu Kang")Warning: plotting the first 10 out of 15 attributes; use max.plot = 15 to plot
all
plot(jw, main = "Jurong West")Warning: plotting the first 9 out of 15 attributes; use max.plot = 15 to plot
all
7.5.2 Creating owin Object
pg_owin = as.owin(pg)
tm_owin = as.owin(tm)
ck_owin = as.owin(ck)
jw_owin = as.owin(jw)Why: Converting study areas into
owinobjects defines the observation window for point pattern analysis within each area.Functions:
as.owin(): Converts a spatial object into anowinformat.
7.5.3 Combining Childcare Points and the Study Area
childcare_pg_ppp = childcare_ppp_jit[pg_owin]
childcare_tm_ppp = childcare_ppp_jit[tm_owin]
childcare_ck_ppp = childcare_ppp_jit[ck_owin]
childcare_jw_ppp = childcare_ppp_jit[jw_owin]- Why: Combining points with their respective study areas allows for localized point pattern analysis.
Rescaling point patterns:
childcare_pg_ppp.km = rescale.ppp(childcare_pg_ppp, 1000, "km")
childcare_tm_ppp.km = rescale.ppp(childcare_tm_ppp, 1000, "km")
childcare_ck_ppp.km = rescale.ppp(childcare_ck_ppp, 1000, "km")
childcare_jw_ppp.km = rescale.ppp(childcare_jw_ppp, 1000, "km")Why: Rescaling the data to kilometers facilitates comparison across different study areas.
Functions:
rescale.ppp(): Rescales the coordinates of point pattern objects.
Visualizing rescaled point patterns:
par(mfrow=c(2,2))
plot(childcare_pg_ppp.km, main="Punggol")Warning in default.charmap(ntypes, chars): Too many types to display every type
as a different characterWarning: Only 10 out of 61 symbols are shown in the symbol mapplot(childcare_tm_ppp.km, main="Tampines")Warning in default.charmap(ntypes, chars): Too many types to display every type
as a different characterWarning: Only 10 out of 89 symbols are shown in the symbol mapplot(childcare_ck_ppp.km, main="Choa Chu Kang")Warning in default.charmap(ntypes, chars): Too many types to display every type
as a different characterWarning: Only 10 out of 61 symbols are shown in the symbol mapplot(childcare_jw_ppp.km, main="Jurong West")Warning in default.charmap(ntypes, chars): Too many types to display every type
as a different characterWarning: Only 10 out of 88 symbols are shown in the symbol map
7.5.4 Computing KDE
par(mfrow=c(2,2))
plot(density(childcare_pg_ppp.km, sigma=bw.diggle, edge=TRUE, kernel="gaussian"), main="Punggol")
plot(density(childcare_tm_ppp.km, sigma=bw.diggle, edge=TRUE, kernel="gaussian"), main="Tempines")
plot(density(childcare_ck_ppp.km, sigma=bw.diggle, edge=TRUE, kernel="gaussian"), main="Choa Chu Kang")
plot(density(childcare_jw_ppp.km, sigma=bw.diggle, edge=TRUE, kernel="gaussian"), main="Jurong West")
- Why: Computing KDE for each area helps identify and compare spatial distribution patterns within different regions.
7.5.5 Computing Fixed Bandwidth KDE
par(mfrow=c(2,2))
plot(density(childcare_ck_ppp.km, sigma=0.25, edge=TRUE, kernel="gaussian"), main="Chou Chu Kang")
plot(density(childcare_jw_ppp.km, sigma=0.25, edge=TRUE, kernel="gaussian"), main="Jurong West")
plot(density(childcare_pg_ppp.km, sigma=0.25, edge=TRUE, kernel="gaussian"), main="Punggol")
plot(density(childcare_tm_ppp.km, sigma=0.25, edge=TRUE, kernel="gaussian"), main="Tampines")
- Why: Using a fixed bandwidth allows for direct comparison of KDE results across different study areas with a uniform smoothing parameter.
8. Nearest Neighbor Analysis
8.1 Testing Spatial Point Patterns Using Clark and Evans Test
clarkevans.test(childcareSG_ppp, correction="none", clipregion="sg_owin", alternative=c("clustered"), nsim=99)
Clark-Evans test
No edge correction
Z-test
data: childcareSG_ppp
R = 0.55631, p-value < 2.2e-16
alternative hypothesis: clustered (R < 1)Why: The Clark and Evans test determines whether a point pattern is more clustered, random, or regular compared to a Poisson distribution.
Functions:
clarkevans.test(): Performs the Clark and Evans test for spatial point patterns.
8.2 Clark and Evans Test: Choa Chu Kang Area
clarkevans.test(childcare_ck_ppp, correction="none", clipregion=NULL, alternative=c("two.sided"), nsim=999)
Clark-Evans test
No edge correction
Z-test
data: childcare_ck_ppp
R = 0.95577, p-value = 0.5087
alternative hypothesis: two-sided8.3 Clark and Evans Test: Tampines Planning Area
clarkevans.test(childcare_tm_ppp, correction="none", clipregion=NULL, alternative=c("two.sided"), nsim=999)
Clark-Evans test
No edge correction
Z-test
data: childcare_tm_ppp
R = 0.77884, p-value = 6.569e-05
alternative hypothesis: two-sided- Why: Performing the Clark and Evans test on different areas allows for localized analysis of spatial point patterns to identify variations in clustering.